It’s hard to say exactly when some started to turn on America’s favorite legging-wearing pastime — it may have been about the time last year a studio in the East Village introduced a version for dogs — but yoga is reveling in less nirvana these days.

What was once a novelty has now become insufferable to many New Yorkers, and no one better encapsulates that disenchantment than Nick Rosen, the subject of the current documentary “Enlighten Up!” (That very un-Zen exclamation point is theirs.)

The film’s director, Kate Churchill, is a die-hard believer in the idea that practicing yoga can transform anyone — so in the film, she recruits the skeptical Rosen as her guinea pig. He enrolls in classes and heads to far-flung India to meet with holy men in hopes of reaching a spiritual awakening. Does it happen?

Does the Dalai Lama own a PlayStation 3?

But Rosen’s not the only one falling out of love with the activity. According to a study by Yoga Journal, 15.8 million American adults practiced yoga in 2008, down from 16.5 million the year before.

Julia Pontecorvo, a 23-year-old production assistant, is one of those who gave her yoga mat the heave-ho.

“For something that’s billed as a great way to relax and a great form of exercise, I didn’t end up feeling the next day like I got anything out of it,” she says. “I didn’t feel more cleansed or toned or all that stuff they advertise.”

“I was doing it, but it was OK,” says Nadja Mark, a 32-year-old Brooklyn grant writer. “But then I just had to call bulls – – – one day when they were telling me that I could put my hands in the air and massage my liver. After a while, I felt like an idiot.”

“It goes along with having a certain level of disposable income and time,” says Jeffrey MacIntyre, a New York tech consultant and an officer of a Facebook group called

“F – – – Yoga.

“It’s not unlike eating all-organic or the other trappings of bourgeoisie life, which is implicitly saying, ‘I’ve got the time and money to care about things like this.’ There’s a sort of class aspect to it.”

The Post phoned Rosen to get his bullet points for what irks him so much about yoga. To counter, we called Lauren Hanna, director of Sonic Yoga. Downward-dog fight!

Yoga Skeptics vs. Yoga Believers

Yoga Skeptic Nick Rosen’s Point:Yoga is About as Ancient as Bollywood

“The thing that’s always repeated in the press is, ‘Yoga, this 5,000-year-old practice.’ That’s just hokum,” Rosen says. “There is yoga that’s a few thousand years old, but it has absolutely not traits in common with the current yoga.” Ancient yoga was more about attaining enlightenment and had little to do with physical movement. Modern yoga, which involves a combo of stretching, breathing and spirituality, didn’t develop until the 1930s in India, and Rosen says it was influenced tremendously by the West. India was under colonial rule. “Some speculate that some yoga poses were taken from British military exercises,” he says.

Yoga Believer Lauren Hanna’s Counterpoint: “He is right to a point,” Hanna says. “Yes, the asanas [poses] were not a huge part of the ancient teachings. Many of the asanas we see are more modern, but I don’t agree that the poses were influenced by the West. Most of the poses created in the 1950s by [Tirumalai] Krishnamacharya were influenced by the Indian martial arts, dance and Indian physical practices.”

Skeptic Point:Yoga Isn’t Really Exercise

According to a study by the American Council on Exercise, yoga isn’t exactly the expressway to fitness. The study showed practitioners didn’t improve cardiovascular health, and that a typical 50-minute class of hatha yoga burned the same number of calories as a slow, 50-minute walk. Power yoga didn’t burn as many calories as calisthenices.

Hanna’s Counterpoint: “I definitely disagree with that,” Hanna says. “I’ve witnessed students of mine lose 30 pounds or more. If we look at just the postures, then yes, some styles of yoga are very gentle, and I don’t think that if you did those you’d get fit. But it’s not just the physical. If you’re walking the yoga path, there’s a whole series of teachings and moral principles around living life in the simplicity and not overindulging.”

Skeptic Point:People Who Practice Are Nauseatingly Homogenous

Julia Pontecorvo, who quit yoga, describes them as “a very liberal, very granola, very hippie, very environmentally friendly crowd” – 72.2 percent of whom are women, according to Yoga Journal. Pontecorvo says the lack of diversity is one thing that drove her away.

Hanna’s Counterpoint: “Yes, people who do yoga tend to be more environmentally aware and concerned about humanity,” Hanna says. “But at my studio, we get mostly actors and musicians and I wouldn’t say they’re necessarily crunchy. I think there’s more variety than she’s giving credit to.”